3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 125 · 40 questions

How to do it in your head (Hundreds first): Keep the first number as it is and split the second into hundreds, tens and ones. Add (or take away) the hundreds first, then the tens. Finish with the ones — bridge through a ten if you need to.

1. 1.705 − 555 =
2. 2.601 + 455 =
3. 3.157 + 402 =
4. 4.498 + 492 =
5. 5.625 − 249 =
6. 6.875 − 718 =
7. 7.526 + 401 =
8. 8.497 − 173 =
9. 9.265 + 525 =
10. 10.858 − 591 =
11. 11.164 + 171 =
12. 12.922 − 155 =
13. 13.507 − 316 =
14. 14.446 − 116 =
15. 15.543 − 125 =
16. 16.561 + 643 =
17. 17.774 − 335 =
18. 18.760 + 243 =
19. 19.697 + 598 =
20. 20.978 − 123 =
21. 21.365 + 475 =
22. 22.620 − 135 =
23. 23.846 − 555 =
24. 24.662 − 207 =
25. 25.726 + 127 =
26. 26.663 − 511 =
27. 27.503 + 345 =
28. 28.458 − 161 =
29. 29.517 − 259 =
30. 30.524 − 199 =
31. 31.621 + 246 =
32. 32.951 − 831 =
33. 33.950 − 187 =
34. 34.776 − 165 =
35. 35.550 + 664 =
36. 36.706 + 623 =
37. 37.140 + 505 =
38. 38.696 − 356 =
39. 39.525 − 261 =
40. 40.698 − 489 =

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